Monitoring vital signs is traditionally done on supine patients at rest. Field based measurements are typically done with a care giver or researcher controlling the person's position (e.g., posture) and degree of movement in order to minimize movement artefacts such as orthstatic changes and effects on the body due to work effort of orientation. Normally tests are performed under various conditions in a clinic manually, using such devices as blood pressure cuffs or using treadmills and stop watches for exertion fitness tests.
Measuring vital signs over time (in the field) provides more useful information for understanding a person's physiological state. However, body position and activity level are key factors that affect a person's vital signs and hence the interpretation thereof.
Information of the biomechanical context of a person allows the person's vital signs to be measured and interpreted remotely. Biomechanical sensors include, for example, tri axial accelerometers and gyroscopes which determine the posture and activity level of a person. Biomechanical sensors which form part of, or are time synchronised to a vital sign monitor, afford the opportunity to take measurements that, until now, would not be practical or useful because the person's movement or posture could have a greater effect than the variations sought. In contrast, embodiments of the present invention can determine a normal state of the person under different activity levels and postures and hence determine an abnormal state. In addition, embodiments of the present invention may be used to determine the probability of dehydration when the person is in the field (not in the clinic) and wherein the movement and posture of the person is not directed by the clinician.
These and other advantages may be provided by one or more embodiments of the present invention.